// ═══════════════════════════════════════════════════════
//  PROJECT MNEMOSYNE — SESSION ROOMS (Issue #1171)
// ═══════════════════════════════════════════════════════
//
// Groups memories by session into holographic chambers.
// Each session becomes a wireframe cube floating in space.
// Rooms are arranged chronologically along a spiral.
// Click a room to fly inside; distant rooms LOD to a point.
//
// Usage from app.js:
//   SessionRooms.init(scene, camera, controls);
//   SessionRooms.updateSessions(sessions);   // [{id, timestamp, facts[]}]
//   SessionRooms.update(delta);              // call each frame
//   SessionRooms.getClickableMeshes();       // for raycasting
//   SessionRooms.handleRoomClick(mesh);      // trigger fly-in
// ═══════════════════════════════════════════════════════

const SessionRooms = (() => {

  // ─── CONSTANTS ───────────────────────────────────────
  const MAX_ROOMS        = 20;
  const ROOM_SIZE        = 9;          // wireframe cube edge length
  const ROOM_HALF        = ROOM_SIZE / 2;
  const LOD_THRESHOLD    = 55;         // distance: full → point
  const LOD_HYSTERESIS   = 5;          // buffer to avoid flicker
  const SPIRAL_BASE_R    = 20;         // spiral inner radius
  const SPIRAL_R_STEP    = 5;          // radius growth per room
  const SPIRAL_ANGLE_INC = 2.399;      // golden angle (radians)
  const SPIRAL_Y_STEP    = 1.5;        // vertical rise per room
  const FLY_DURATION     = 1.5;        // seconds for fly-in tween
  const FLY_TARGET_DEPTH = ROOM_HALF - 1.5; // how deep inside to stop

  const ROOM_COLOR       = 0x7b5cff;   // violet — mnemosyne accent
  const POINT_COLOR      = 0x9b7cff;
  const LABEL_COLOR      = '#c8b4ff';
  const STORAGE_KEY      = 'mnemosyne_sessions_v1';

  // ─── STATE ────────────────────────────────────────────
  let _scene    = null;
  let _camera   = null;
  let _controls = null;

  let _rooms        = [];   // array of room objects
  let _sessionIndex = {};   // id → room object

  // Fly-in tween state
  let _flyActive   = false;
  let _flyElapsed  = 0;
  let _flyFrom     = null;
  let _flyTo       = null;
  let _flyLookFrom = null;
  let _flyLookTo   = null;
  let _flyActiveRoom = null;

  // ─── SPIRAL POSITION ──────────────────────────────────
  function _spiralPos(index) {
    const angle = index * SPIRAL_ANGLE_INC;
    const r     = SPIRAL_BASE_R + index * SPIRAL_R_STEP;
    const y     = index * SPIRAL_Y_STEP;
    return new THREE.Vector3(
      Math.cos(angle) * r,
      y,
      Math.sin(angle) * r
    );
  }

  // ─── CREATE ROOM ──────────────────────────────────────
  function _createRoom(session, index) {
    const pos = _spiralPos(index);
    const group = new THREE.Group();
    group.position.copy(pos);

    // Wireframe cube
    const boxGeo   = new THREE.BoxGeometry(ROOM_SIZE, ROOM_SIZE, ROOM_SIZE);
    const edgesGeo = new THREE.EdgesGeometry(boxGeo);
    const edgesMat = new THREE.LineBasicMaterial({
      color: ROOM_COLOR,
      transparent: true,
      opacity: 0.55
    });
    const wireframe = new THREE.LineSegments(edgesGeo, edgesMat);
    wireframe.userData = { type: 'session_room_wireframe', sessionId: session.id };
    group.add(wireframe);

    // Collision mesh (invisible, for raycasting)
    const hitGeo = new THREE.BoxGeometry(ROOM_SIZE, ROOM_SIZE, ROOM_SIZE);
    const hitMat = new THREE.MeshBasicMaterial({
      visible: false,
      transparent: true,
      opacity: 0,
      side: THREE.FrontSide
    });
    const hitMesh = new THREE.Mesh(hitGeo, hitMat);
    hitMesh.userData = { type: 'session_room', sessionId: session.id, roomIndex: index };
    group.add(hitMesh);

    // LOD point (small sphere shown at distance)
    const pointGeo = new THREE.SphereGeometry(0.5, 6, 4);
    const pointMat = new THREE.MeshBasicMaterial({
      color: POINT_COLOR,
      transparent: true,
      opacity: 0.7
    });
    const pointMesh = new THREE.Mesh(pointGeo, pointMat);
    pointMesh.userData = { type: 'session_room_point', sessionId: session.id };
    pointMesh.visible = false;  // starts hidden; shown only at LOD distance
    group.add(pointMesh);

    // Timestamp billboard sprite
    const sprite = _makeTimestampSprite(session.timestamp, session.facts.length);
    sprite.position.set(0, ROOM_HALF + 1.2, 0);
    group.add(sprite);

    // Inner ambient glow
    const glow = new THREE.PointLight(ROOM_COLOR, 0.4, ROOM_SIZE * 1.2);
    group.add(glow);

    _scene.add(group);

    const room = {
      session,
      group,
      wireframe,
      hitMesh,
      pointMesh,
      sprite,
      glow,
      pos: pos.clone(),
      index,
      lodActive: false,
      pulsePhase: Math.random() * Math.PI * 2
    };

    _rooms.push(room);
    _sessionIndex[session.id] = room;

    console.info('[SessionRooms] Created room for session', session.id, 'at index', index);
    return room;
  }

  // ─── TIMESTAMP SPRITE ────────────────────────────────
  function _makeTimestampSprite(isoTimestamp, factCount) {
    const canvas  = document.createElement('canvas');
    canvas.width  = 320;
    canvas.height = 72;
    const ctx = canvas.getContext('2d');

    // Background pill
    ctx.clearRect(0, 0, 320, 72);
    ctx.fillStyle = 'rgba(20, 10, 40, 0.82)';
    _roundRect(ctx, 4, 4, 312, 64, 14);
    ctx.fill();

    // Border
    ctx.strokeStyle = 'rgba(123, 92, 255, 0.6)';
    ctx.lineWidth = 1.5;
    _roundRect(ctx, 4, 4, 312, 64, 14);
    ctx.stroke();

    // Timestamp text
    const dt = isoTimestamp ? new Date(isoTimestamp) : new Date();
    const label = _formatDate(dt);
    ctx.fillStyle = LABEL_COLOR;
    ctx.font = 'bold 15px monospace';
    ctx.textAlign = 'center';
    ctx.fillText(label, 160, 30);

    // Fact count
    ctx.fillStyle = 'rgba(200, 180, 255, 0.65)';
    ctx.font = '12px monospace';
    ctx.fillText(factCount + (factCount === 1 ? ' fact' : ' facts'), 160, 52);

    const tex    = new THREE.CanvasTexture(canvas);
    const mat    = new THREE.SpriteMaterial({ map: tex, transparent: true, opacity: 0.88 });
    const sprite = new THREE.Sprite(mat);
    sprite.scale.set(5, 1.1, 1);
    sprite.userData = { type: 'session_room_label' };
    return sprite;
  }

  // ─── HELPERS ──────────────────────────────────────────
  function _roundRect(ctx, x, y, w, h, r) {
    ctx.beginPath();
    ctx.moveTo(x + r, y);
    ctx.lineTo(x + w - r, y);
    ctx.quadraticCurveTo(x + w, y, x + w, y + r);
    ctx.lineTo(x + w, y + h - r);
    ctx.quadraticCurveTo(x + w, y + h, x + w - r, y + h);
    ctx.lineTo(x + r, y + h);
    ctx.quadraticCurveTo(x, y + h, x, y + h - r);
    ctx.lineTo(x, y + r);
    ctx.quadraticCurveTo(x, y, x + r, y);
    ctx.closePath();
  }

  function _formatDate(dt) {
    if (isNaN(dt.getTime())) return 'Unknown session';
    const pad = n => String(n).padStart(2, '0');
    return `${dt.getFullYear()}-${pad(dt.getMonth() + 1)}-${pad(dt.getDate())}  ${pad(dt.getHours())}:${pad(dt.getMinutes())}`;
  }

  // ─── DISPOSE ROOM ────────────────────────────────────
  function _disposeRoom(room) {
    room.wireframe.geometry.dispose();
    room.wireframe.material.dispose();
    room.hitMesh.geometry.dispose();
    room.hitMesh.material.dispose();
    room.pointMesh.geometry.dispose();
    room.pointMesh.material.dispose();
    if (room.sprite.material.map) room.sprite.material.map.dispose();
    room.sprite.material.dispose();
    if (room.group.parent) room.group.parent.remove(room.group);
    delete _sessionIndex[room.session.id];
  }

  // ─── PUBLIC: UPDATE SESSIONS ─────────────────────────
  // sessions: [{id, timestamp, facts:[{id,content,category,strength,...}]}]
  // Sorted chronologically oldest→newest; max MAX_ROOMS shown.
  function updateSessions(sessions) {
    if (!_scene) return;

    const sorted = [...sessions]
      .sort((a, b) => new Date(a.timestamp) - new Date(b.timestamp))
      .slice(-MAX_ROOMS);  // keep most recent MAX_ROOMS

    // Remove rooms no longer present
    const incoming = new Set(sorted.map(s => s.id));
    for (let i = _rooms.length - 1; i >= 0; i--) {
      const room = _rooms[i];
      if (!incoming.has(room.session.id)) {
        _disposeRoom(room);
        _rooms.splice(i, 1);
      }
    }

    // Add / update
    sorted.forEach((session, idx) => {
      if (_sessionIndex[session.id]) {
        // Update position if index changed
        const room = _sessionIndex[session.id];
        if (room.index !== idx) {
          room.index = idx;
          const newPos = _spiralPos(idx);
          room.group.position.copy(newPos);
          room.pos.copy(newPos);
        }
      } else {
        _createRoom(session, idx);
      }
    });

    saveToStorage(sorted);
    console.info('[SessionRooms] Updated:', _rooms.length, 'session rooms');
  }

  // ─── PUBLIC: INIT ─────────────────────────────────────
  function init(scene, camera, controls) {
    _scene    = scene;
    _camera   = camera;
    _controls = controls;
    console.info('[SessionRooms] Initialized');

    // Restore persisted sessions
    const saved = loadFromStorage();
    if (saved && saved.length > 0) {
      updateSessions(saved);
    }
  }

  // ─── PUBLIC: UPDATE (per-frame) ───────────────────────
  function update(delta) {
    if (!_scene || !_camera) return;

    const camPos = _camera.position;

    _rooms.forEach(room => {
      const dist = camPos.distanceTo(room.pos);

      // LOD toggle
      const threshold = room.lodActive
        ? LOD_THRESHOLD + LOD_HYSTERESIS   // must come closer to exit LOD
        : LOD_THRESHOLD;

      if (dist > threshold && !room.lodActive) {
        room.lodActive = true;
        room.wireframe.visible = false;
        room.sprite.visible    = false;
        room.pointMesh.visible = true;
      } else if (dist <= threshold && room.lodActive) {
        room.lodActive = false;
        room.wireframe.visible = true;
        room.sprite.visible    = true;
        room.pointMesh.visible = false;
      }

      // Pulse wireframe opacity
      room.pulsePhase += delta * 0.6;
      if (!room.lodActive) {
        room.wireframe.material.opacity = 0.3 + Math.sin(room.pulsePhase) * 0.2;
        room.glow.intensity = 0.3 + Math.sin(room.pulsePhase * 1.4) * 0.15;
      }

      // Slowly rotate each room
      room.group.rotation.y += delta * 0.04;
    });

    // Fly-in tween
    if (_flyActive) {
      _flyElapsed += delta;
      const t = Math.min(_flyElapsed / FLY_DURATION, 1);
      const ease = _easeInOut(t);

      _camera.position.lerpVectors(_flyFrom, _flyTo, ease);

      // Interpolate lookAt
      const lookNow = new THREE.Vector3().lerpVectors(_flyLookFrom, _flyLookTo, ease);
      _camera.lookAt(lookNow);
      if (_controls && _controls.target) _controls.target.copy(lookNow);

      if (t >= 1) {
        _flyActive = false;
        if (_controls && typeof _controls.update === 'function') _controls.update();
        console.info('[SessionRooms] Fly-in complete for session', _flyActiveRoom && _flyActiveRoom.session.id);
        _flyActiveRoom = null;
      }
    }
  }

  // ─── EASING ───────────────────────────────────────────
  function _easeInOut(t) {
    return t < 0.5 ? 2 * t * t : -1 + (4 - 2 * t) * t;
  }

  // ─── PUBLIC: GET CLICKABLE MESHES ─────────────────────
  function getClickableMeshes() {
    return _rooms.map(r => r.hitMesh);
  }

  // ─── PUBLIC: HANDLE ROOM CLICK ────────────────────────
  function handleRoomClick(mesh) {
    const { sessionId } = mesh.userData;
    const room = _sessionIndex[sessionId];
    if (!room || !_camera) return null;

    // Fly into the room from the front face
    _flyActive   = true;
    _flyElapsed  = 0;
    _flyActiveRoom = room;

    _flyFrom = _camera.position.clone();

    // Target: step inside the room toward its center
    const dir = room.pos.clone().sub(_camera.position).normalize();
    _flyTo = room.pos.clone().add(dir.multiplyScalar(FLY_TARGET_DEPTH));

    _flyLookFrom = _controls && _controls.target
      ? _controls.target.clone()
      : _camera.position.clone().add(_camera.getWorldDirection(new THREE.Vector3()));
    _flyLookTo = room.pos.clone();

    console.info('[SessionRooms] Flying into session room:', sessionId);
    return room.session;
  }

  // ─── PERSISTENCE ──────────────────────────────────────
  function saveToStorage(sessions) {
    if (typeof localStorage === 'undefined') return;
    try {
      localStorage.setItem(STORAGE_KEY, JSON.stringify({ v: 1, sessions }));
    } catch (e) {
      console.warn('[SessionRooms] Failed to save to localStorage:', e);
    }
  }

  function loadFromStorage() {
    if (typeof localStorage === 'undefined') return null;
    try {
      const raw = localStorage.getItem(STORAGE_KEY);
      if (!raw) return null;
      const parsed = JSON.parse(raw);
      if (!parsed || parsed.v !== 1 || !Array.isArray(parsed.sessions)) return null;
      console.info('[SessionRooms] Restored', parsed.sessions.length, 'sessions from localStorage');
      return parsed.sessions;
    } catch (e) {
      console.warn('[SessionRooms] Failed to load from localStorage:', e);
      return null;
    }
  }

  function clearStorage() {
    if (typeof localStorage !== 'undefined') {
      localStorage.removeItem(STORAGE_KEY);
      console.info('[SessionRooms] Cleared localStorage');
    }
  }

  // ─── PUBLIC API ───────────────────────────────────────
  return {
    init,
    updateSessions,
    update,
    getClickableMeshes,
    handleRoomClick,
    clearStorage,
    // For external inspection
    getRooms: () => _rooms,
    getSession: (id) => _sessionIndex[id] || null,
    isFlyActive: () => _flyActive
  };

})();

export { SessionRooms };